Ovarian cancer antigen CA 125 enhances the invasiveness of the endometriotic cell line EEC 145

OBJECTIVE: Ovarian cancer antigen CA 125 is used widely for diagnostic and therapeutic evaluation of ovarian cancer. Although the initial description of CA 125 was in 1981, its function is still unknown. In collagen gel system the invasiveness of the endometriotic cell line EEC 145 is enhanced by a proteinaceous factor in peritoneal fluid mimicking molecular features of CA 125. Therefore we hypothesize that this factor is CA 125. METHODS: The influence of heat-treated peritoneal fluid on the invasiveness of the endometriotic cell line EEC 145 and several human carcinoma cell lines (EJ28, RT112, AN3, RL95-2, HEC-1-A, HeLa, MCF7, T-47D, and SK-OV-3) was investigated in a collagen gel invasion assay by addition of (1); 10% heat-treated peritoneal fluid, (2); peritoneal fluid after immunoprecipitation with antibodies directed to CA 125, and (3); purified CA 125. RESULTS: The invasion index of the endometriotic cell line EEC 145 significantly increased from 4.78 +/- 0.98 to 6.57 +/- 1.58 (P = .0001) by addition of 10% heat-treated peritoneal fluid to the culture medium. The invasion-promoting effect of peritoneal fluid was abolished by reduction of the CA 125 concentration through immunoprecipitation and was mimicked in a dose-dependent manner by addition of CA 125 to the culture medium. The invasiveness of the investigated human carcinoma cell lines was not affected by heat-treated peritoneal fluid or CA 125. CONCLUSION: The results are consistent with the hypothesis that CA125 can influence invasiveness in a benign endometriotic cell line. Copyright (C) 1999 by the Society for Gynecologic Investigation.